Windshield cleaning systems, in which the washing liquid is supplied to jets for the purpose of improving the effect of the washing system, which jets are arranged on the wiper arm-and-blade assembly and are moving to and fro with it, are already known. In a known embodiment of this kind the washing liquid is supplied through a pipe within a bore in a wiper shaft, whereby the end of the washing liquid pipe at the drive end of the wiper shaft axially engages into a pot-like connecting piece from which a tube stud for connecting a washing liquid supply tube is sticking out. In such a system the washing liquid pipe is moving to and fro like the wiper shaft, whereas the connecting piece is non-rotatably fixed because otherwise, the washing liquid supply tube would considerably be strained during operation of the cleaning system and there would be danger of tearing off after a longer time of operation. In an embodiment according to the DE-OS 36 43 476 or the DE-GM 81 00 709 the connecting piece is fixed onto a frame via an extension arm radially sticking out. In both cases not only a protection against twisting is realized by this extension arm, but also the connecting piece is rigidly fixed onto a stationary member.
Due to the necessary relative movement in such embodiments a seal between the end of the washing liquid pipe and the connecting piece is provided, which seal meets high requirements and still works reliably even after a longer time of operation. Because of fixing the connecting piece stable in form in a rigid manner this is not guaranteed in the known embodiments. Relatively big wear of the bearing surfaces between the end and the connecting piece is also disadvantageous.